Thyroid Stimulating Hormone
Understanding Thyroid Stimulating Hormone
What is Thyroid Stimulating Hormone?
The thyroid-stimulating hormone (TSH) test measures the amount of TSH in the blood. Doctors can use TSH test results to diagnose thyroid disorders. The thyroid hormone plays an important role in regulating weight, body temperature, and even mood. Having an overactive or underactive thyroid can cause health issues that interfere with daily life.
A high TSH and low thyroid hormone level can indicate primary hypothyroidism whereas a low TSH and a high thyroid hormone level can indicate primary hyperthyroidism. Normal TSH ranges can alter depending on a person’s age, sex, and body weight.The normal range usually falls between 0.4 and 4.0 mU/l. Thyroid tests are done every 4-6 weeks initially and then after 6 to 12 months once stable.
Interpreting Thyroid Stimulating Hormone results
Interpretations
The TSH normal range may vary from lab to lab.
The TSH normal range for different age groups is given below:
Patients (Age) TSH Normal Range
|
Premature Infants (28-36 Weeks) |
|
|
1st Week of Life |
0.20-27.90 mIU/L |
|
Term Infants (>37 Weeks) |
|
|
Serum or Cord Blood |
1.00-39.00 mIU/L |
|
1-2 Days |
3.20-34.60 mIU/L |
|
3-4 Days |
0.70-15.40 mIU/L |
|
5 Days-4 Weeks |
1.70-9.10 mIU/L |
|
1-11 Months |
0.80-8.20 mIU/L |
|
1-19 Years |
0.50-4.30 mIU/L |
|
≥20 Years |
0.40-4.50 mIU/L |
|
Pregnancy |
|
|
First Trimester |
0.26-2.66 mIU/L |
|
Second Trimester |
0.55-2.73 mIU/L |
|
Third Trimester |
0.43-2.91 mIU/L |
- If your TSH level is increased, it usually indicates that you have hypothyroidism. Hashimoto’s thyroiditis is the most common cause of primary hypothyroidism.
- If your TSH level is decreased, it usually indicates hyperthyroidism. Graves' disease, multinodular goiter, toxic nodule are some of the common causes of hyperthyroidism.
Note: TSH normal range levels show circadian variation (fluctuates during the 24-hour cycle), reaching peak levels between 2-4 am and are at a low between 6-10 pm.
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